Abstract: Catalytic cross coupling reactions are among the most widely used strategies for C—C and C—N bond formation in organic synthesis. However, when two or more electrophiles (usually aryl (pseudo)halides) are present in the reactants, controlling site selectivity becomes critical. The most common approach to controlling selectivity involves using different substrates to access different products (substrate control). A potentially more general approach is to manipulate selectivity through choice of catalyst/ligand or reaction conditions. This presentation will describe our recent work on ligand-controlled C4-selective cross-coupling of 2,4-dichloropyridine derivatives. The mechanistic origin of solvent-controlled selectivity in cross-couplings of chloroaryl triflates will also be discussed. In addition to streamlining synthetic methods, this work provides insight into mechanistic details that could facilitate future catalyst design.